Steps to reproduce

1. Open Safari
2. Starting at URL: https://wordpress.com/setup/with-theme-assembler/pattern-assembler
3. Add two patterns to the page.
4. Select "Select styles"
5. Select a premium style with a background color.

What I expected

To see the background color of the style applied to my patterns. It works as expected in Chrome.

What happened instead

The patterns maintain a background color of white, making it seem like the style is much less expressive and boring.

Browser / OS version

Safari, latest.

Screenshot / Video